In recent years, we have come increasingly to recognize that ideas have a history and that not the least important chapters of this history have to do with thematic or conceptual aspects of literature and the arts, although these aspects should be studied in conjunction with the history of philosophy, of religion, and of the sciences. When these fields are surveyed together, important patterns of relationship emerge indicating a vast community of reciprocal influence, a continuity of thought and expression including many traditions, primarily literary, religious, and philosophical, but frequently including contact with the fine arts and even, to some extent, with science.

Here we may observe that at least one modern philosophy of history is built on the assumption that ideas are the primary objectives of the historian's research. Let us quote once more from R. G. Collingwood: ``History is properly concerned with the actions of human beings. Regarded from the outside, an action is an event or series of events occurring in the physical world; regarded from the inside, it is the carrying into action of a certain thought. The historian's business is to penetrate to the inside of the actions with which he is dealing and reconstruct or rather rethink the thoughts which constituted them. It is a characteristic of thoughts that, in re-thinking them we come, ipso facto, to understand why they were thought.'' Such an understanding, although it must seek to be sympathetic, is not a matter of intuition. ``History has this in common with every other science: that the historian is not allowed to claim any single piece of knowledge, except where he can justify his claim by exhibiting to himself in the first place, and secondly to any one else who is both able and willing to follow his demonstration, the grounds upon which it is based. This is what was meant, above, by describing history as inferential. The knowledge in virtue of which a man is an historian is a knowledge of what the evidence at his disposal proves about certain events.'' It is obvious that the historian who seeks to recapture the ideas that have motivated human behavior throughout a given period will find the art and literature of that age one of his central and major concerns, by no means a mere supplement or adjunct of significant historical research.